Rétention des ions Plomb (II) en milieu acide par ultrafiltration assistée par les micelles

L'ultrafiltration assistée par les micelles (UFAM) a été utilisée pour la récupération des ions plomb (II) en milieu acide (Phosphorique et perchlorique) à la température 318K. Le dodécylsulfate de sodium (SDS) a été choisi comme agent tensioactif. Des taux de rétention de 99% ont été obtenus dans des conditions optimales de pression, de concentration en SDS, de vitesse de circulation du fluide et de pourcentage du volume filtré. L'équilibre d'échange ionique qui s'effectue entre le contre ion de la micelle et le cation métallique ajouté (Pb2+), a été caractérisé par une contante Ke(Na+/Pb2+)=1,39. Afin d'étudier la performance de l'UFAM dans les milieux acides, l'étude a été effectuée à concentration de Pb(II) constante et en variant le pH. À des pH supérieurs à 1,8 la rétention est supérieure à 95%.The increasing contamination of urban and industrial waste water by toxic metal ions is a worrying environmental problem. These inorganic micro-pollutants are of considerable concern because they are non-biodegradable, highly toxic and in some cases have a probable carcinogenic effect. If directly discharged into the sewage system they may seriously affect the operation of biological treatment systems and render the activated sludge unsuitable for application to agricultural land.The traditional techniques for the removal of metal ions from aqueous effluents are incapable of reducing concentrations to the levels required by law (reduction or lime precipitation) or prohibitively expensive (ion exchange, activated carbon adsorption or electrolytic removal). The use of membrane separation processes to treat waste water containing toxic metal ions is today an attractive and suitable technique, and it can easily be included in the process, which is the reason why membrane separations are being used more and more frequently. Separations can be carried at room temperature, the modular membrane surface can be easily adjusted to the wastewater flows, and various industrial membranes are now available. In order to retain metallic ions, reverse osmosis (or at least nanofiltration) can be used, due to the size of the ions in aqueous solutions. However, the usual permeate fluxes of reverse osmosis membranes are limited and require high transmembrane pressure, which makes the process expensive.During the last decade, there has been a constantly increasing level of interest and research efforts in order to improve the performances of surfactant-based separation processes. In the present study an attempt is made to remove lead(II) ions from synthetic aqueous solutions by micellar-enhanced ultrafiltration (MEUF) using the anionic surfactant sodium dodecylsulfate (SDS). The study has been carried out at a temperature of 318 ºK and on a laboratory scale.Ultrafiltration experiments were carried out with a tangential cell system. The inlet flux was held constant (up to 0.5 m.s-1) and the drop in pressure was varied from 1 to 3 bars by restricting the outlet tube. Polysulfone membranes with a molecular weight cut-off (MWCO) of 10,000 Da and an effective filtration area of 30 cm2 were used. The influence of the operating parameters on permeate flux and lead rejection was studied. Rejection coefficients of 99% are reached under optimal conditions of pressure, feed concentration in SDS, tangential velocity of the feed, and percent filtered volume.An ionic exchange model has been used to study the interaction between the lead cation (Pb2+) and sodium dodecylsulfate micelles. The model used to fit the experimental data is an ionic micelle in which the electric double layer is divided into a diffuse outside layer and a Stern layer inside the shear surface. Assuming that divalent cations are strongly attached to the micellar surface and located specifically in the Stern layer of the micelle, it has been found that adsorption in the Stern layer is well described by a Langmuir isotherm. From this isotherm, ion exchange constants for Pb2+ with the Na+ counter-ion have been determined Ke (Na+ /Cd2+) -=1.39, and have been compared with those obtained for other cations (Cd2+, Mg2+) in the same media. In order to determine the performance of the MEUF process in acidic streams, studies were performed at constant cation concentrations and various pH values. The pH variation was obtained by the addition of HClO4 or H3PO4. Rejection remains higher than 95% provided the pH is maintained higher than 1.8

Operational framework based on modeling languages to support product repository implementation.

Part 3: Tools and MethodologiesInternational audienceEmbracing Product Lifecycle Management approach involves integrating a product repository in the company information system. From customer's needs to disposal stage, several product representations exist. The product repository purpose is to secure consistency of one product representation with the others. This paper presents an operational modeling framework that supports product repository implementation. In order to ensure consistency, this framework identifies correspondences between entities of languages (“trade” languages and standard languages). The presented concepts are illustrated with correspondences between language entities of product designed and productplanned to be built Bills of Materials

The Mechanisms of Construction of Generic Product Configuration with the Help of Business Object and Delay Differentiation

Organised by: Cranfield UniversityProduct configuration has a central role in PLM application. The generic product configuration which factories the similarities between the product types, is used to facilitate the production by permitting delay differentiation. In this research, the role of business object in the construction of generic product configuration is studied. Then the rules used in the procedure of structuring the generic and specific configuration are presented. These rules are based on the” variability points” method. The concept is identifying the major variability’s of different products by finding the dependencies of their properties. The industrial case of the culinary articles is then studied.Mori Seiki – The Machine Tool Compan

A process model based methodology to support conflict management

The product design development has increasingly become a collaborative process. Conflicts often appear in the design process due to multi-actors interactions. Therefore, a critical element of collaborative design would be conflict situations resolution. In this paper, a methodology, based on a process model, is proposed to support conflict management. This methodology deals mainly with the conflict resolution team identification and the solution impact evaluation issues. The proposed process model allows the design process traceability and the data dependencies network identification; which making it be possible to identify the conflict resolution actors as well as to evaluate the selected solution impact. Copyright © 2006 IFAC